---
title: "CVE-2026-89633: Linux Kernel smb client - Out-of-Bounds Read/Write"
description: "Linux kernel smb client contains an out-of-bounds read/write caused by unvalidated DataOffset in coalesce_t2(), letting attackers cause memory corruption or crash, exploit requires crafted SMB packets."
url: https://panop.io/threat-heartbeat/CVE-2026-89633/
---

# CVE-2026-89633 Linux Kernel smb client - Out-of-Bounds Read/Write

Linux kernel smb client contains an out-of-bounds read/write caused by unvalidated DataOffset in coalesce\_t2(), letting attackers cause memory corruption or crash, exploit requires crafted SMB packets.

CVSS base score 9.8 /10

Critical

CISA KEV

Not listed

Public exploit

None known

Authentication

Not required

EPSS

0.47% chance of exploitation in 30 days

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-89633)

## Details

Type

Out-of-Bounds Read/Write

Impact

Denial Of Service

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Published

11 September 2026

Updated

15 October 2026

## Vendor fix

Update to the latest Linux kernel version containing the fix for this vulnerability.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

## References

- [https://nvd.nist.gov/vuln/detail/CVE-2026-89633](https://nvd.nist.gov/vuln/detail/CVE-2026-89633)
- [https://git.kernel.org/stable/c/36d01415d881d5326a0dd3384f781cd7e69aff2d](https://git.kernel.org/stable/c/36d01415d881d5326a0dd3384f781cd7e69aff2d)
- [https://git.kernel.org/stable/c/033bc80019f07d158630df4e69b19a49010f54f1](https://git.kernel.org/stable/c/033bc80019f07d158630df4e69b19a49010f54f1)
- [https://git.kernel.org/stable/c/6343c1da561962688f203362d80d6a3bfa39fa1b](https://git.kernel.org/stable/c/6343c1da561962688f203362d80d6a3bfa39fa1b)
- [https://git.kernel.org/stable/c/672cf86aa6aa0fb4012ce4c3b3498df42ad67a4e](https://git.kernel.org/stable/c/672cf86aa6aa0fb4012ce4c3b3498df42ad67a4e)

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## What this record can't tell you

- Whether you run the affected software, and where
- Whether an attacker can actually reach and exploit it
- The misconfigurations that never get a CVE number
- What it would cost the business, ranked into what to fix first

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